2022 Hazelnut Pest Management Guide for the Willamette Valley

Nik Wiman, Jay W. Pscheidt and Marcelo Moretti
EM 8328 | April 2022 |

This guide lists recommendations for insect, mite and disease control in hazelnut orchards. The chemicals, formulations and application rates listed here are based on label directions, research and orchard experience.

Pest management depends on producers and their knowledge of the orchard and its characteristics. Producers must weigh several factors: cultivar, tree size, tree density, canopy characteristics, pest complex and pest history. Consider all these factors when choosing which chemicals to apply and at what rates. Other variables include the amount of water used per acre, and the method of application.

Trade name products are mentioned as examples only. Occasionally, manufacturers register different formulations of a product that contain a different concentration of active ingredient. This does not mean that OSU Extension either endorses these products or intends to discriminate against products not mentioned. Consult product labels to determine whether their use confers advantages over the products listed in this guide.

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Always refer to the pesticide label for use instructions. It is the legal document.

Producers ask two common questions about the chemical control of insects and diseases:

  • “How much chemical do I use per acre?”
  • “What is the least amount of water I need per acre to apply in my concentrate sprayer?”

The schedule below suggests an amount of formulated product to use per acre, and not the amount of active ingredient. This amount is based on a “typical” orchard of middle age and average tree density, with moderate pest pressure. Less product may be needed in 1- to 4-year-old orchards. Conversely, more chemical (within label limits) may be required for large, mature trees experiencing heavy pressure from multiple pests.

It takes less spray to get good coverage on an orchard with immature trees with limited canopy, but this does not affect the rate of application by volume. For most ground-applied applications, apply products in a minimum of 100 gallons of water per acre. For larger canopies, 150 to 200 GPA of water can improve coverage and efficacy. Always calibrate sprayers to tree size to improve coverage, reduce waste, and avoid drift.

Please be aware of recent regulations governing the application of pesticides outlined in the EPA Worker Protection Standard, particularly the Application Exclusion Zone, which is enforced by Oregon Occupational Safety and Health. All new pesticide labels provide orchard re-entry intervals and personal protection equipment information. See Oregon standards.

Apply pesticides judiciously and promote good relationships with neighbors.

CHECK THE LABEL BEFORE SPRAYING! Also:

  • Make sure any tank-mixes of pesticides are compatible. When in doubt, make a sample mixture in a jar to evaluate compatibility. In some cases, the mixture may not react visibly, but efficacy may be compromised.
  • Most pesticides perform best when water is slightly acidic (a pH of 5–6), and a pH above 7.0 can cause rapid loss of efficacy. Consider testing pH and adjusting water pH prior to mixing, or avoid certain tank mixes. For example, elevated pH of boron spray solution can weaken insecticides when mixed.
  • Use adjuvants and spreader stickers with caution.

See Table 3, Effectiveness of fungicide for eastern filbert blight management.

Rotate pesticides by mode of action (group); do not become reliant on a single group for control.

In this guide, mode of action (MoA) for insecticides is based on the Insecticide Resistance Action Committee (IRAC) classification (irac-online.org). Fungicide mode of action is based on the Fungicide Resistance Action Committee (FRAC) classification.

Premix products may have reduced rates of active ingredients, and may contribute to development of resistance

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Crop stages

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Hazelnut pest control recommendations

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Quick reference guide to herbicides labeled for use in hazelnuts

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Hazelnut pests

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Strategies for using fungicides for managing eastern filbert blight

Fungicides have been useful to suppress or delay development of eastern filbert blight in an orchard of susceptible cultivars such as Ennis or Barcelona. Cultivars such as Jefferson or McDonald, with the single dominant gene for resistance only, need protection the first spring after planting, when located near heavily infected orchards. Fungicides will not remove or eliminate cankers from the tree.

Fungicides are best used to protect susceptible tissue in the spring at budbreak and for the next eight weeks. Most fungicides will last two weeks before another application is needed. This means a total of four applications, starting with the first at budbreak. Although hazelnuts are still susceptible after this period, additional applications have not resulted in consistent, significant disease control.

Because of fungicide resistance issues and resulting label requirements, you may not be able to use the same fungicide for all four applications. Since the EFB fungus has a long (two-year) life cycle, the resistance risk is already low relative to other diseases, such as powdery mildew. Strategies to further minimize this risk include alternating or tank-mixing fungicides with different modes of action. The Fungicide Resistance Action Committee has categorized, grouped and assigned numbers to the modes of action.

Alternating fungicides with different modes of action has been effective to manage EFB. Research has not identified any one alternating strategy as better than any other strategy. We have several fungicide groups to choose from, including FRAC groups 3, 11, M5, M3 and M1. It is suggested that the first application be chlorothalonil or ziram (group M5 or M3) followed by your choice of a Group 3 or Group 11 fungicide. Each of the next two applications would be different from the previous one. An example of this program might be to start with Bravo (or any of its generics, Group M5) at bud break, followed by Flint Extra (Group 11) two weeks later, then Tilt (Group 3) two weeks after that, and ending with Cabrio (Group 11). Use of multisite products such as chlorothalonil (Group M5), ziram (Group M3) or copper-based products (Group M1) for all four applications would also be acceptable.

Do not just alternate fungicides with different trade names, as they might have the same mode of action. Some fungicide premixes already combine two fungicides with different modes of action, generally a Group 3 and Group 11 fungicide. These products cannot be used for every application because they do not allow more than two sequential applications before switching to a different product with a different mode of action. If you use these premixes, you must use an M5, M3 or M1 fungicide in the rotation. An example of this program might be to start with Bravo (M5) at bud break, followed by Stratego (3 + 11) or QuiltXcel (3 + 11) two weeks later, then the same product two weeks after that, but ending with Bravo.

You can make your own tank-mixes. Since tank-mixing can be expensive, growers have asked about reducing the rate of each product in the tank. Research to date has shown that a half rate of Echo 90 DF (Group M5) tank-mixed with either Tilt (Group 3) or Cabrio (Group 11) is effective to manage EFB. Combining fungicide resistance theory and research on EFB in Oregon suggests we should use a half rate of chlorothalonil tank-mixed with a full rate of a Group 3 fungicide or a half rate of a Group 11 fungicide. An example of this program might be:

First application: A full rate of Bravo (M5) at budbreak

Second application, two weeks later: A mix of Cabrio (11) plus Echo 90DF (M5), each at half rate.

Third application, two weeks later: A mix of Tilt (3) at full rate plus Echo 90DF (M5) at half rate.

Fourth application, two weeks later: A mix of Cabrio (11) plus Echo 90DF (M5), each at half rate.

Research has indicated that addition of a surfactant provides better disease control than a fungicide alone. Numerous products can break the surface tension of water to get better coverage of plant tissue. They also can help keep the fungicide solution in contact with the plant, reducing wash-off during rain events. Unless otherwise stated on the label, add a surfactant with a fungicide. Copper-based products have traditionally been applied with a horticultural mineral oil. Newer fungicides may be mixed with silicone-based or nonionic surfactants. Be careful, as several fungicides may already come formulated with a surfactant and/or specifically say NOT to add these products. For example, do not add a surfactant to Bravo or Quadris Top.

Effectiveness of fungicides for eastern filbert blight management

Follow the ‘RULES’ for fungicide stewardship

Rotate or mix fungicides of different chemical groups.

Use labeled rates.

Limit total number of applications.

Educate yourself about fungicide activity, mode of action, and class—as well as resistance management practices.

Start a fungicide program with multisite mode of action materials.

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Toxicology information for insecticides used in hazelnuts

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OSU resources for plant protection

Information on plant protection is available from several sources at Oregon State University:

OSU Integrated Plant Protection Center. Online weather data and degree day information for insect pests and diseases

Pacific Northwest Plant Disease Management Handbook

Pacific Northwest Insect Management Handbook

Pacific Northwest Weed Management Handbook

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Using pesticides safely

Always read the label

The single most important approach to pesticide safety is to read the pesticide label before each use and then follow the directions. If still in doubt after reading the label, contact a person qualified to help evaluate the hazard of the chemical and its use. Qualified people include Extension specialists, county educators, pesticide product representatives and retailers.

Pesticides are toxic and should be handled with care — but they can be used safely if you follow recommended precautions. Follow all label requirements, and strongly consider any recommendations for additional personal protective clothing and equipment. In addition to reading and following the label, other major factors in the safe and effective use of pesticides are the pesticide applicator’s qualifications, common sense and positive attitude. Always take all safety precautions when using pesticides.

In case of accidents involving pesticides, see your doctor at once. It will help your doctor to know exactly which pesticide is involved. The label on the container gives this information. Take to the physician the pesticide label or information from the label, such as the product name, registration number of the U.S. Environmental Protection Agency, common name and percentage of active ingredient and first aid instructions. If the label cannot be removed, take along the pesticide container (if not contaminated), but do not take it into the hospital or doctor’s office.

Pesticide safety checklist

  • Use pesticides only when necessary and as part of an Integrated Pest Management program.
  • Always read the label and follow the instructions.
  • Do not allow children to play around sprayers or mixing, storage, and disposal areas.
  • Wear appropriate protective clothing and equipment.
  • Never eat, drink, or smoke while handling pesticides.
  • Avoid drift into non-target areas and pesticide runoff into streams, rivers, lakes, irrigation ponds and canals.
  • Avoid spilling materials on skin or clothing.
  • Have access to clean water, soap, and first aid supplies.
  • Keep pesticides in a dry and locked storage area away from food and feed.
  • Triple rinse or pressure rinse empty containers and dispose or recycle in accordance with state and local regulations.
  • Stay out of recently sprayed areas until the spray has dried, and observe the restricted entry intervals specified on the pesticide label.
  • Follow the pre-harvest interval on the pesticide label before harvesting crops or gardens and before allowing livestock to graze fields.

Emergency response for exposure and spills

For any pesticide exposure emergency, dial 911.

First aid for exposure is indicated on the pesticide label.

For information on poison emergency treatment call the National Poison Center at 800-222-1222.

For emergency information related to pesticide spills contact the Oregon Emergency Response System at 800-452-0311.

Non-emergency information

General pesticide information The National Pesticide Information Center provides objective, science-based information about pesticides and pesticide-related topics. Call 800-858-7378.

Pesticide licensing and regulation The Oregon Department of Agriculture regulates most aspects of pesticide use in the State of Oregon. Vall 503-986-4635.

Worker protectionThe federal Worker Protection Standard for Agricultural Pesticides protects agricultural workers from pesticide exposure at work. The Oregon Occupational Safety and Health Administration is the state agency responsible for administering the WPS in Oregon. For information on WPS requirements for employers, call 800-922-2689.

Pesticide waste — The Oregon Department of Environmental Quality regulates the disposal of pesticide waste in the State of Oregon. Visit or call 503-229-5263.The Tricounty Hazardous Waste and Recycling Program conducts periodic collection events for unused pesticides in Hood River, Sherman, and Wasco counties. Most chemical distributors offer plastic pesticide container recycling.

Trade-name products and services are mentioned as illustrations only. This does not mean that the Oregon State University Extension Service either endorses these products and services or intends to discriminate against products and services not mentioned.

Use pesticides safely!

  • Wear protective clothing and safety devices as recommended on the label. Bathe or shower after each use.
  • Read the pesticide label—even if you’ve used the pesticide before. Follow closely the instructions on the label (and any other directions you have).
  • Be cautious when you apply pesticides. Know your legal responsibility as a pesticide applicator. You may be liable for injury or damage resulting from pesticide use.

About the authors

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